Synthetic resins are lightweight and can be easily processed, while having such excellent characteristic features that substrates can be designed according to the application. Thus, synthetic resins are currently indispensable and important materials used in a wide range of fields. One of the important characteristic features of the synthetic resins is high electric-insulating properties. Therefore, synthetic resins have been frequently used for various components of electric products. However, because of their excellent electric-insulating properties, there is a problem in that the products can become electrified through friction or the like.
Electrified resins have a problem in that they draw surrounding dirt and dust, spoiling their appearance. In addition, in electric products, such as computers and other precision instruments, there are cases where electrification leads to abnormal circuit operation. Further, there is a problem due to electric shock. Electric shock passed from resin to the human body causes an unpleasant feeling. In addition, the resin may induce an explosion in the presence of inflammable gas or dust particulates. Therefore, in order to solve such a problem, resins are generally subjected to an electrification-prevention process; a commonly known, a method being to add an antistatic agent to the synthetic resin. Antistatic agents can be roughly divided into permanent antistatic agents that copolymerize antistatic units within resin molecules, and kneading-type antistatic agents added during the processing fabrication of a resin. Of these, the cheap and easily processable kneading-type antistatic agents have been widely used.
The kneading-type antistatic agent demonstrates an effect when it bleeds out onto the surface of the synthetic resin. However, there is a problem in that the persistence of the antistatic effect is insufficient as a result of its removal from the surface of the resin through friction and washing with water and the like. In addition, if the antistatic agent has poor compatibility with the synthetic resin, the antistatic agent inside the resin quickly bleeds out onto the surface thereof, thereby causing a problem in that it loses its effect within several days or weeks.
For improving such persistence, polymeric antistatic agents have been studied. For example, Patent Document 1 discloses, in the presence of 5 to 80 parts by weight (parts by mass) (as calculated by solid components) of diene-based copolymer latex including 50 percent by weight (percent by mass) or more of conjugated diene-based monomer (A), an antistatic resin composition that includes:
100 parts by weight (parts by mass) of a resin composed of (A) 10 to 100 percent by weigh (percent by mass) of a graft copolymer obtained by graft copolymerization of 5 to 100 percent by weight (percent by mass) of a monomer represented by the following general formula (1):
where R1, R2 and R3 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and n represents an integer of 3 to 50 with 95 to 20 parts by weight (parts by mass) of a monomer composition made of 95 to 0 percent by weight (percent by mass) of at least one monomer selected from the group consisting of aromatic vinyl compounds, methacrylate esters, acrylate esters, and vinyl cyan compounds, and(B) 90 to 0 percent by weight (percent by mass) of a thermoplastic resin having compatibility with the above graft copolymer, where the percentage of the diene copolymer is 5 to 30 percent by weight (percent by mass); and
0.05 to 10 parts by weight (parts by mass) of a sulfonic-acid monovalent metal salt or a carboxylic-acid monovalent metal salt of an alkyl fluoride-containing compound having at least one perfluoroalkyl group represented by the following general formula (2):Rf-X-M  (2)where Rf represents a perfluoroalkyl group having 4 to 15 carbon atoms, X represents —SO3— or —COO—, and M represents a monovalent metal.
In addition, Patent Document 2 discloses a thermoplastic resin composition including: (A) 1 to 50 parts by weight (parts by mass) of polyether esteramide having a polyether ester unit of 95 to 10 percent by weight (percent by mass), composed of (a) an aminocarboxylic acid or lactam having 6 or more carbon atoms, or diamine and dicarboxylic acid salts having 6 or more carbon atoms, (b) poly(alkylene oxide) glycol having a number-average molecular weight of 200 to 6,000, and (c) dicarboxylic acid having 4 to 20 carbon atoms; (B) 99 to 50 parts by weight (parts by mass) of a polycarbonate resin; and (C) 0 to 49 parts by weight (parts by mass) of a styrene-based thermoplastic resin, which are mixed so that the total amount of (A)+(B)+(C) is 100 parts by weight (parts by mass).
Furthermore, Patent Document 3 discloses a polymeric antistatic agent represented by the general formula (1):
where R1 represents a hydrocarbon group, R2 represents a hydrogen atom or a hydrocarbon group, or a hydrocarbon group or a hydrophilic group having an ester group, m represents a numeral of 1 or more, and n represents a numeral of 2 or more. In addition, paragraph of Patent Document 3 describes that “In the general formula (1), R1 is a hydrocarbon group, preferably an alkylene group having 2 to 4 carbon atoms. A (R1—O)m portion can be obtained by addition polymerization of alkylene oxide or the like, such as ethylene oxide, propylene oxide, butylene oxide, α-olefin oxide or styrene oxide. In the case of forming the (R1—O)m portion by the addition of alkylene oxide or the like, R1 is determined by the kind of alkylene oxide or the like to be added. The polymerization of the alkylene oxide or the like to be added is not limited to any particular configuration and may be a homo-polymerization of one kind of alkylene oxide or the like, or a random copolymerization, block copolymerization, random/block copolymerization, or the like, of two or more kinds of alkylene oxides or the like. R1 is most preferably an ethylene group. When R1 includes two or more different groups, one of those is preferably an ethylene group”. In addition, paragraph [0009] describes that “R2 represents a hydrogen atom or a hydrocarbon group. Examples of the hydrocarbon groups include an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group and a cycloalkenyl group”.
Furthermore, as an antistatic composition that satisfies both persistence and instantaneous effect, Patent Document 4 discloses an antistatic composition specifically containing: a polymer (A) that contains a monomer unit represented by the following general formula (1):
where R1 represents an alkylene group, R2 represents a hydrogen atom, a halogen atom or a hydrocarbon group, X represents a hydrogen atom, a hydrocarbon group, an isocyanate residue, a hydrocarbon group having an ester group, or an anionic hydrophilic group, and m represents a numeral of 1 or more; and a low-molecular weight anionic organic compound (B). In addition, paragraph [0012] of Patent Document 4 describes that “In the above general formula (1), the (R1—O)m portion can be obtained by addition polymerization of phenol or phenol having a substituent to alkylene oxide or the like, such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran (1,4-butylene oxide), long-chain α-olefin oxide, or stylene oxide. In the case of forming the (R1—O)m portion by addition polymerization of alkylene oxide or the like, the kind of (R1—O) is determined by the kind of alkylene oxide or the like to be added. The polymerization of alkylene oxide or the like to be added is not limited to any particular configuration and may be a homo-polymerization of one kind of alkylene oxide or the like, or a random copolymerization, block copolymerization, random/block copolymerization, or the like, of two or more kinds of alkylene oxides or the like. If the (R1—O)m portion is polyalkylene oxide, R1 is an alkylene group, preferably an alkylene group having 2 to 4 carbon atoms, most preferably an ethylene group. In addition, if the (R1—O)m portion is formed by copolymerization of two or more alkylene oxides or the like, one of those is preferably ethylene oxide”.
Patent Document 1: Japanese Patent Laid-Open No. 63-101444, Claims
Patent Document 2: Japanese Patent Laid-Open No. 62-273252, Claims
Patent Document 3: Japanese Patent Laid-Open No. 2000-34330, Claims, [0008] and [0009]
Patent Document 4: Japanese Patent Laid-Open No. 2002-60734, Claims, [0012]